Gene-Trac® Testing
SiREM is a leader in the field of molecular genetic testing relating to biodegradation of chlorinated solvents. SiREM was the first commercial laboratory to offer Dehalococcoides testing under our Gene-Trac® banner and is once again leading the field by providing functional gene analysis for vinyl chloride reductase with our Gene-Trac®-VC test.
SiREM has close working relationships/intellectual property agreements with academic and industry partners including DuPont* and Stanford University**, keeping SiREM at the forefront of this dynamic field and providing first-rate analysis and technical support to our customers. Gene-Trac® testing is offered through exclusive license agreements with *Du Pont de Nemours & Co. (United States Patent, US6894156B2 [Hendrickson and Ebersole]) and **Stanford University (United States Patent Application USSN 60/598459 [Spormann and McCarty])
Questions About Gene-Trac® Testing
Q. What type and volume of sample is required for Gene-Trac® testing?
A. Gene-Trac® testing is performed using groundwater (1 Liter), biomass collected on membrane filters, or sediment (50 grams). Contact SiREM for specific sampling protocols.
Q. Does SIREM provide sampling containers?
A. Yes. SiREM provides Gene-Trac® sampling filters or containers free of charge
Q. Is more than one groundwater or soil sample required when multiple Gene-Trac® tests are performed at one site location?
A. No. Once the DNA is extracted from a sample, multiple Gene-Trac® tests can be performed.
Q. How many Gene-Trac® samples are required to characterize a site?
A. In order to provide sufficient replication, spatial coverage, and to assess variability within a site, samples should be collected from locations with varying geochemistry and contaminant concentrations to provide the most useful information. SiREM generally recommends a minimum of three samples for each sampling event, although more should be considered for large or heterogeneous sites.
Q. What are the implications of a positive Gene-Trac® Dehalococcoides test?
A. A positive Gene-Trac® Dhc test provides strong evidence that Dehalococcoides organisms are present at a site and may facilitate complete dechlorination of chloroethenes and other compounds where geochemical conditions are appropriate. Follow-on tests for the VC-reductase gene (vcrA) (Gene-Trac® VC) may be used to confirm that any detected Dhc are capable of dechlorination of vinyl chloride.
Q. What concentration of Dehalococcoides is associated with significant dechlorination rates to ethene?
A. Dehalococcoides concentrations in excess of 1 x 107 gene copies/ liter groundwater typically promote active dechlorination and production of ethene. The highest Dhc concentrations typically observed at field sites are in the 109 gene copies per liter range. For further information please contact SiREM.
Q. If ethene is detected at a site, is there still a need for Dehalococcoides testing?
A. Yes. The detection of low concentrations of ethene at chloroethene contaminated sites doesn't rule out the abiotic production of ethene or co-metabolic (biotic) production of ethene. The acceptance of MNA remedies by the US EPA requires convincing evidence that biological processes are active under site conditions. Gene-Trac® testing, in conjunction with chemical analyses, increases the confidence that active biodegradation is occurring at the location of contamination.
Q. Can all Dehalococcoides organisms degrade vinyl chloride efficiently?
A. No. Some strains of Dehalococcoides are unable to convert VC to ethene effectively. At some sites, Dhc may be detected, but dechlorination of VC to ethene could be insufficient because the strain may lack the enzyme vinyl chloride reductase (vcrA). Gene-Trac® VC targets a gene called vinyl chloride reductase (vcrA) that is only present in some Dehalococcoides and which are efficient at VC degradation.
Q. What are the implications of a positive Gene-Trac® VC test?
A. A detect in a Gene-Trac® VC test indicates the site is much less likely to accumulate highly toxic vinyl chloride under bioremediation compared to a site that lacks this gene (i.e., non-detect).
Q. What is the Purpose of Dehalobacter Testing (Gene-Trac® Dhb)?
A. Dehalobacter microorganisms are capable of degradation a variety of chlorinated compounds including 1,2-DCA, 1,1,1-TCA and chloroform, the quantification of Dehalobacter is of particular interest where these compounds are present at a site.
